I think I own pretty much any book on skiing technique pubblished during the last 6-7 years. I have no doubt that Harb's Anybody can be an expert skier, vol I e II is by far the best in terms of contents. But, it does not suit PSIA teaching and certification purposes (although some Ski Schools will not call the firing squad if they catch you teaching using PMTS concepts). And, I believe that Harb is working on a newer edition of his books (title is going to change, 3 volumes instead of 2, dvd's).
My second favorite is probably the Skiing and the Art of Carving (I suggest you buy also Technical Skills for Alpine Skiing by the same authors).
I also like "All-Mountain Skier : The Way to Expert Skiing" by M. Elling. But, it does not address the basic techniques except for a quick review in the first part.
Lito's book and videos are excellent although I do not like the editorial aspect of his book.
Ski the Whole Mountain: How to Ski Any Condition at Any Time
by Eric Deslauriers, Rob Deslauriers, Hank Devre is also a good one, to ski double blacks (maybe extreme ones and all sort of stuff. Maybe it is better if you take their clinics....
The Skier's Edge by Ron Lemaster is not bad. I must say that however I never really thought too much of this book as a teaching tool. Perhaps at very advanced levels. The physics is nice, biomechanics in my opinion is not really there, instead.
The New Guide to Skiing: A Step-by-Step Guide in Color, Revised Edition
by Martin Heckelman is not bad. Lots of ideas for drills, etc..
I have more books, of course, some from Europe, about Powder, Technique, etc.. but you cannot read them all or you will never ski!
I like books written the way Harald Harb does (I am PSIA, don't read more than there is here, but as a holder of a Ph.D. degree in science, I recognize when a book has a scientific approach and when it does not). Also, the more volumes, the better: it shows that skiing is not a little thing, it gives respectability to the discipline.